^^^this. Unless you are having issues ... FTF, stove pipe, etc. ... do a return to battery check. If the RSA will RTB, no need to change springs.

I've found the stock OEM RSA is good to about 250 PF ... that is a 200 grain bullet at 1250 fps muzzle velocity. Above a PF=250 you may need a 22# or 24# RSA to prevent slide-frame slam.

Porting the barrel and slide is one solution, however adding a longer threaded barrel with a ported compensator and fine tuning with the weight of the recoil spring for the specific load may be a better option ... at least to get to where you want to be. Generally, a 22# RSA will help with full power 10mm loads.

https://www.youtube.com/watch?v=wFzXm-0sMrk

If flash is an issue, try Alliant BE-86. Burn rate falls between Unique and Power Pistol. BE-86 meters very well, similar to Power Pistol.

http://www.alliantpowder.com/reloaders/RecipePrint.aspx?gtypeid=1&weight=165&shellid=30&bulletid=41&bdid=1246

http://www.alliantpowder.com/reloaders/RecipePrint.aspx?gtypeid=1&weight=165&shellid=30&bulletid=330&bdid=1249

X2 on PowerPistol.

I also read that comment by the Alliant tech ... interestingly he said, back in 2014, that BE-86 was slightly faster burn rate than PP (BE-84), some place between Unique and PP. Later articles I've read said BE-86 was between PP and Longshot, closer to Herco burn rate. Very confusing.

I just picked up a pound of BE-86 to work up for muzzle flash. After reading The_Shadow's comment on another thread, I might also give another try with Longshot.

Thanks for the information on BE-86, it appears more promising than I figured ... I've been seriously thinking about BE-86 as an alternative to Power Pistol, mainly because most bear problems happen at night and muzzle flash could be a major issue. I'll be picking up a pound of BE-86 and working up loads for CEB 190gr Solid Copper.

I'll post chrono results and my opinion on muzzle flash vis-a-vis Power Pistol when I get the tests done. I'll check for accuracy/group with the BE-86, but I'm not really concerned about it since most legit Bear Defense is going to be inside of 10yds or so ... or inside the tent

Glock G40 OEM 6" barrel

BULLET WEIGHT: 165gr Rainier Plated

CASE MFR.: Starline

PRIMER: CCI300

POWDER: Alliant Power Pistol

CHARGE WEIGHT: 8.4 grains

OVERALL CARTRIDGE LENGTH: 1.250"

VELOCITY: 1267 fps

OTHER DETAILS: Good plinking/target round with very good bullet stability/accuracy to 75 yds

Glock G40 with 7" KKM barrel


BULLET WEIGHT: 200 gr Hornady XTP

CASE MFR.: Starline

PRIMER: CCI350

POWDER: Accurate #9

CHARGE WEIGHT: 12.8 gr.  (12.5 gr in Glock OEM 6" barrel)

OVERALL CARTRIDGE LENGTH: 1.260"

VELOCITY: 1302 fps (1228 fps in Glock OEM 6" barrel)

OTHER DETAILS: Excellent Black Bear Defense/Hunting load. Glock OEM RSA spring a bit light for 7" barrel, might experience slide-frame slam without heavier spring.

While it is not necessary to size Starline new casings, I do so as to ensure uniform case dimensions and uniform taper crimp.

Using a 7" KKM 10mm Match barrel in the G40, I got 1326 fps at 10' through the Pro Chrono with the 190gr CEB Solid, which equates to about 1336 fps ~ 1340 fps mv, depending on which muzzle velocity calculator is used.

Starline Brass (Unfired) sized through RCBS die .988"
CCI 300 Primer
8.9 gr Power Pistol
Taper Crimp .419"
190gr CEB Solid @ 1.254" COAL

At 8.9 gr PP, the CCI primer showed more than the usual flattening, but no case head breech face/ejector marks, or primer piercing/sooting. Fired case head measured .426", max case bulge .428".

After working up a max load with Power Pistol, I read that Power Pistol may have a blinding flash in low light ... not so good for a Bear Defense load. I'll have to give this a try at dark on my local pistol range. If the flash is too much, next try is BE-86 flash suppressed version of Power Pistol.

After reading Alasken's comments on penetration, a bit lower muzzle velocity, which is what I expect with BE-86, might be a good trade-off to get less flash.